Overnight rains brought the mercury several degrees down in the national capital on Tuesday morning. A thick layer of fog enveloped the city disrupting flight operations at the IGI airport. The low was recorded at 11.7 degree Celsius, four degrees above normal but three degrees less than Monday's minimum of 14.6 degrees. Heavy fog somewhat added to the chill factor in the capital which was having warm and pleasant days for the last couple of weeks. Around 20 flights were rescheduled at the IGI airport as thick fog led to runway visibility dropping to around 100 metres.A mild sun came out as the day progressed. Unexpected showers coupled with strong winds lashed the city last night, bringing the mercury down from above normal levels witnessed during the day. The maximum had been recorded at 26.2 degree C before the rains but it came down by over six degrees after the showers.The rains, which were the result of a western disturbance, were accompanied by hailstorm in some parts of the city.In most parts of Punjab and Haryana, though there was a dip in temperature, the minimum was still above normal. The rains at this time of the season are considered beneficial for the rabi crops. The Met has forecast a rise in day as well as night temperatures with possibility of light showers at some places in the region during the next two days.